This invention lies in the field of gas heated stoves or ranges incorporating a vitreous ceramic hot plate whereunder is positioned at least one burner assembly. Each burner assembly utilizes an electric light or ignition device of the glowing wire type.
Depending on the nature of the cooking process and on the quality of utensils used, the topside, (that is, the side facing a user) of a gas-heated vitreous ceramic hotplate may heat up to temperatures of the order of 550.degree. C. The low thermal conductivity of conventional vitreous ceramic materials precludes fast heat dissipation of accumulated heat laterally through the hotplate away from the cooking zone region in the cooking zone region when a cooking procedure has been terminated. The cooling of hot cooking zone regions in a hot plate occurs substantially by convection to the airflow sweeping over the surfaces of the hotplate region. Consequently, it takes generally between about 40 and 60 minutes for such a heated hotplate area of cool to a reasonably safe temperature (e.g. below about 100.degree. C.). For a user's safety, it is therefore highly important that the "hot" condition of a cooking zone region of a vitreous ceramic hotplate should continue to be visibly indicated even after an adjacent associated burner has been switched off until after the plate itself has cooled to a safe-to-touch temperature (e.g. about 60.degree. C. or below).
Owing to the stored thermal energy in a heated cooking zone region of a vitreous ceramic hot plate, it is possible, especially at low temperature, or slow cooking stages, for the intervals of time between successive "on" phases of an associated adjacent burner to be of the order of 10 minutes, or even longer, so that a user may easily be mistaken in thinking that such a burner has been previously switched off. Moreover, a warning light would provide a constant warning signal as to the prevailing operative state of a burner at the actual burner side adjacent the cooking zone region and would also reduce the risk of such a burner being accidentally left "on" after cooking has been completed.
Since a gas jet burner characteristically shows its normal glow-pattern only after an initial starting up period of approximately 60 seconds and since, before then, a burner appears to be dark underneath its associated vitreous ceramic hotplate, it is an advantage to provide an immediate signal in the vicinity of the burner site to show a user that the burner is switched "on", as this will assist the user in the correct placing of cooking pans and also in the immediate detection of an accidentally switched-on burner.
The gas jet burner which is covered by the vitreous ceramic hotplate is automatically controlled and burns within a fully enclosed space with associated exhaust flue. It is of vital importance that the ignition of such a burner should be utterly dependable under any circumstances, that is to say, not only when the cooker switch is moved to the "on" position, but also during an intermittent, cyclic operation of the burner which is required to maintain pre-selected energy stages. For this purpose, it is currently common practice to provide a high-tension spark igniter. Igniters of the glowing wire type, on the other hand, are less commonly used in the prior art.
While spark igniters, in view of the inevitably very brief spark duration, are not themselves suitable to act at the same time as warning or position indicator devices, it is possible to combine an "off/on" warning signal function with the ignition function in the case of an electric lighter of the glowing wire type.